The purpose of this study is to better understand the etiopathogenesis of fibromyalgia. Our current subject groups consist of 25 fibromyalgia (FM) patients with gradual symptom onset, 10 FM patients with traumatic symptom onset, 25 community residents with FM who have not sought treatment for their painful symptoms (nonpatients), and 13 healthy controls. All subjects undergo pain threshold and sensory testing, single photon emission computed tomographic (SPECT) imaging of brain regional cerebral blood flow (rCBF) during resting conditions, and lumbar puncture to collect cerebrospinal fluid for radioimmunoassay of substance P. We plan to continue subject recruitment until we have 25 FM patients with traumatic onset, 50 nonpatients with FM, and 50 controls.